Electrical push-button switch with photo-electrical switching elements

ABSTRACT

An electric switch comprising a push-button, a casing slidably supporting the push-button, and a return spring acting on the push-button to urge the push-button to a raised position, away from the bottom of the casing. The casing includes two hollow portions facing one another and constituted of transparent material, a light source in one hollow portion and a photoelectric element in the other hollow portion. The pushbutton carries a screen for blocking communication between the light source and the photoelectric element when the push-button is depressed to an operative position. The hollow portions are constituted by two housings projecting from the bottom of the casing and made of transparent plastic material and the pushbutton includes an integral stem slidable in the casing and provided with two cavities in its free end corresponding in shape to the hollow portions to receive and cover the same when the push-button is depressed.

"United States Patent [191 Astier et al.

[ ELECTRICAL PUSH-BUTTON SWITCH WITH PHOTO-ELECTRICAL SWITCHING ELEMENTS [75] Inventors: Paul Georges Astier, La

Seyne-sur-Mer; Pierre Canaby, Sainte-Anne Toulon, both of France [73] Assignee: Etat Francais, Paris, France [22] Filed: Nov. 20, 1974 [21] App]. No.: 525,651

[ Sept. 16, 1975 Primary Examiner.lames W. Lawrence Assistant ExaminerE. R. LaRoche Attorney, Agent, or Firm-Waters, Schwartz & Nissen ABSTRACT An electric switch comprising a push-button, a casing slidably supporting the push-button, and a return spring acting on the push-button to urge the pushbutton to a raised position, away from the bottom of the casing. The casing includes two hollow portions facing one another and constituted of transparent material, a light source in one hollow portion and a photoelectric element in the other hollow portion. The push-button carries a screen for blocking communication between the light source and the photoelectric element when the push-button is depressed to an operative position. The hollow portions are constituted by two housings projecting from the bottom of the casing and made of transparent plastic material and the pushbutton includes an integral stem slidable in the casing and provided with two cavities in its free end corresponding in shape to the hollow portions to receive and cover the same when the push-button is depressed.

10 Claims, 5 Drawing Figures PATENTEUSEPISIBTS 3,906,222

sum 3 0f 3 ELECTRICAL PUSH-BUTTON SWITCH WITH PHOTO-ELECTRICAL SWITCHING ELEMENTS BACKGROUND a. Field of the Invention The invention relates to an electric switch controlled by a push button and comprising a photoelectric element. The invention is particularly concerned with the construction of such switches.

b. Prior Art Conventional push button switches comprise a slidable button on which one presses and a push member fixed to the button which acts mechanically on an electrical contact.

Several types of push button switches are known.

In a first type, the contact is closed all the time the push button is depressed and it opens as soon as the push button is released. This is the case, for example, for push buttons for door bells. Also, the button can be mechanically locked after having been depressed.

In another type, the button is depressed only to pro duce an electric signal and the button is then released and returns to its initial position by elastic means. The electric signal is used, for example, to control a time switch or to control the alternate opening and closing of an electric circuit by acting on a bistable lever.

These have the disadvantage of requiring a mechanically controlled contact which results in wear of the switch after a given number of operations. Furthermore, such switches cannot generally be utilized underwater or in places exposed to rain and moisture without enclosing them in a sealed container because the electric contacts are exposed to the entry of water along the length of the push button.

SUMMARY OF THE INVENTION An object of the invention is to provide a push button switch in which the circuits and electrical contacts are separated in a totally sealed fashion from the push button and in which there is eliminated all mechanical action in the push button and all electrical contact by mechanical means which reduces the wear and allows a total number of operations which is 100 to 1,000 times higher than that of the known switches.

This object is achieved by means of an electrical switch with a push button control comprising a push button which is slidable in a casing and which is urged to an initial position by elastic means, a luminous source and a photo-electric element secured to the casing in facing relation to one another and being separated by a free space; an opaque screen secured to the push button for entering said space when the push button is depressed, and electrical switch means for transforming variations of electrical current produced by said photo-electric element into signals controlling the opening or closing of an electrical circuit.

In one embodiment, the luminous source and the photo-electric element are placed in housings of transparent meterial which isolates them totally from the interior of the casing.

These housings are preferably constituted by two hollow domes made of plastic material projecting from the bottom of the casing.

The push button has an integral stem which is slidable in the casing and which is provided, at its free extremity, with two cavities whose shape corresponds to those of said domes so that they cover them when the push button is depressed.

Preferably, the push button and the stem are made of a transparent or translucent plastic material, for example, methyl methacrylate so that the exposed or front face of the push button is always weakly illuminated by the luminous source.

The switch preferably comprises one or more hollow bosses of transparent material projecting into the interior of the casing, in each of the bosses there is mounted a respective luminous source which is alternately extinguished and lit during each operation of the push button.

The illumination furnished by the luminous source facing the photo-electric element assures at the most a weak illumination, allowing the switch to be found in the dark.

The illumination furnished by the additional luminous sources in the bosses is a stronger illumination which indicates the state of a circuit in the case of a switch which successively controls the opening and the closing of the circuit.

In the latter case, the transparent stem of the push button has lateral grooves slidably receiving a respective boss, and the cavity which receives the housing containing the light source is covered with an opaque lining.

One of the advantages of the push button switch of the invention resides in the absolute protection of its electric circuits against entry of water into the interior of the casing, all the electrical circuits being separated from the casing and placed in sealed housings. Thereby, the switch can be utilized on horizontal panels slightly inclined in a marine environment or a corrosive atmosphere or even immersed in Water.

Another advantage is the possibility of utilizing only static electronic components and eliminating all moving electric switch parts to provide increased resistance to wear and better reliability. The only movable parts are the push buttons and the return spring.

Another advantage is the possibility of fabricating this switch by molding synthetic resin materials such as methyl methacrylate for the transparent parts and polyvinyl chloride for the opaque parts.

Such molded fabrication reduces the costs of manufacture by two to three times as compared to the known switches and provides improved properties of sealing and reliability.

Another advantage is that the mechanical portion of the switch is reduced to a push button and a return spring which is easily constructed and maintained and which provides reliable operation.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a front perspective view of the switch according to the invention partially broken away and in section.

FIG. 2 is an exploded sectional view taken along line IIII in FIG. 1,

FIG. 3 is an exploded sectional view taken along line llI-III in FIG. 1,

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and

FIG. 5 is a schematic electronic circuit diagram.

DETAILED DESCRIPTION FIG. 1 shows a switch 1 with a push button control mprising a casing 2, a push button 3 integral with a m 4 which slides in casing 2, a return spring 5 acting tween the stem and the casing, and a cover 6 which fixed to the casing and has a peripheral rim forming internal abutment for the push button 3. This switch can operate as a continuous action switch close a circuit when the pushbutton is depressed and open it when the push button is released. t can also operate as a bistable switch which altertely acts to open and close a circuit, during each sucssive action on the push button, this being the most rrent type in use. At the bottom of the casing there are formed two holv transparent housings 7a and 7b projecting up- .rdly from the bottom of the casing. The housings are rallel to one another, of circular cross-section and ve rounded tops in the form of domes. One of the usings, for example the housing 7b, contains a light .irce, for example, a lamp 70 or the extremity of an tic fiber emitting a light beam. The other housing 7a ntains a photo-electric element 7d, for example a oto-electric cell or a photo-pile, facing the light urce. Ihe stem 4 has at its free lower extremity, two cavis 8a and 8b, whose shape corresponds to that of usings 7a and 7b such that the housings are received the cavities and covered by the stem when the push tton 3 is depressed. The stem 4 can contain a solid opaque lining 13 in vity 8a, or it can itself be opaque thereat, such that ten the push button is depressed, communication beeen the luminous source and the photo-electric ele- :nt is blocked. This causes a rapid drop in voltage or current intensity emitted by the photo-electric ele- :nt. This rapid variation of current constitutes a signal llized to control the opening or closing of an electric 'cuit. Other suitable means can be used to block communition between the light source and the photo-electric :ment when the push button is depressed. Thus, in- :ad of a complete opaque lining 13 in housing 8a, the ing can be placed only on the face of the wall which sses between the light source and the photo-electric :ment. Altemately, the stem could be made opaque reat. FIG. 2 is a sectional view showing the housings 7a, and the cavities 8a, 8b. There is seen in this figure, )m top to bottom, the cover 6, the push button 3 and integral stem 4, the spring 5, the casing 2 and an at- :hment nut 9 which is screwed on the external reads on casing 2. In FIG. 4 there can be seen the two cavities 8a and in the stem as well as two lateral grooves 10a and b of semi-circular shape. The casing comprises two ditional transparent bosses 11a and 11b projecting wardly from the bottom of the casing. The cavities thin these bosses 11a and 1112 are open to the exter of the casing and each boss contains a luminous urce 12a, 12b. The bosses 11a and 11b are engaged the grooves 10a and 10b and slide therein when the sh button is depressed. Pushbutton 3 and the stem 4 can be constituted of a lnsparent or translucent material such that the light ams from luminous sources 12a and 12b illuminate a front face of the push button 3.

These luminous sources are connected to the electric circuit controlled by the switch. In the case of a bistable switch, they are lit and extinguished alternately during each successive operation and indicate the state of the circuit.

In order to prevent the light emitted by the lamps 12a and 12b from influencing the photo-electric element 7d, the cavity 8a is furnished with internal opaque lining 13. The lamp 7c also illuminates the front face of the push button 3 but with a weaker light beam allowing the push button to be found in the dark.

The elements of the switch according to the invention can be formed by molding synthetic resins which are polymerizable in hot or cold state.

For example, the casing and the element forming the push button and the stem, which is preferably transparent, can be made of methyl methacrylate whereas the opaque cover can be made of polyvinylchloride.

In FIG. 5 there is seen an electronic circuit containing the luminous source and the photo-electric element 7d which is a germanium photodiode. Reference character 13' represents a trigger for shaping signals furnished by the photodiode 7d. Reference character 14 is a bistable double rocker arm and reference character 15 is a transistor, sometimes blocked, sometimes saturated serving as a static switch.

The visible light sources 12a and 12b are connected in parallel to the circuit controlled by the transistor 15.

Of course, without departing from the framework of the invention, numerous modifications and variations will become obvious to those skilled in the switch art. For example; the lamp 70 can be replaced by an electroluminescent diode; the photodiode can be replaced by a photo-transistor; the discreet components of the electronic circuit can be replaced by an integral circuit.

What is claimed is:

1. An electric switch comprising a push button, a casing slidably supporting the push button, said casing having a bottom, resilient means acting on the push button and casing to bias the push button to a raised position away from the bottom of the casing, said casing including two hollow portions facing one another and constituted of transparent material, a light source in one hollow portion and a photo-electric element in the other hollow portion, and means on said push button for blocking communication between said light source and photo-electric element when the push button is depressed to an operative position, said hollow portions being constituted by two housings projecting from the bottom of the casing and made of transparent plastic material.

2. A switch as claimed in claim 1 wherein said push button includes an integral stern slidable on said casing, said stem having a free end facing said hollow portions, said free end being provided with two cavities corresponding in shape to said hollow portions to receive and cover the same when the push button is depressed.

3. A switch as claimed in claim 2 wherein said push button and the stem are constituted of a material which permits passage of light so that the push button is illuminated by the light source.

4. A switch as claimed in claim 3 wherein said casing includes at least one hollow boss projecting into the interior of the casing, and a second light source in said boss, said second light source being alternately lit and extinguished by operation of the push button.

the bottom of the casing.

8. A switch as claimed in claim 1 wherein said housings have rounded tops.

9. A switch as claimed in claim 1 wherein said housings are circular in cross-section.

10. A switch as claimed in claim 1 wherein said casing and push button are constituted of transparent plastic material. 

1. An electric switch comprising a push button, a casing slidably supporting the push button, said casing having a bottom, resilient means acting on the push button and casing to bias the push button to a raised position away from the bottom of the casing, said casing including two hollow portions facing one another and constituted of transparent material, a light source in one hollow portion and a photo-electric element in the other hollow portion, and means on said push button for blocking communication between said light source and photo-electric element when the push button is depressed to an operative position, said hollow portions being constituted by two housings projecting from the bottom of the casing and made of transparent plastic material.
 2. A switch as claimed in claim 1 wherein said push button includes an integral stem slidable on said casing, said stem having a free end facing said hollow portions, said free end being provided with two cavities corresponding in shape to said hollow portions to receive and cover the same when the push button is depressed.
 3. A switch as claimed in claim 2 wherein said push button and the stem are constituted of a material which permits passage of light so that the push button is illuminated by the light source.
 4. A switch as claimed in claim 3 wherein said casing includes at least one hollow boss projecting into the interior of the casing, and a second light source in said boss, said second light source being alternately lit and extinguished by operation of the push button.
 5. A switch as claimed in claim 4 wherein said stem has a lateral groove in which said boss is slidably engaged.
 6. A switch as claimed in claim 2 wherein said means for blocking communication between the light source and the photo-electric element comprises an opaque lining in the cavity of the stem which is to receive the hollow portion with the photo-electric element.
 7. A switch as claimed in claim 1 wherein said housings are parallel to one another and perpendicular to the bottom of the casing.
 8. A switch as claimed in claim 1 wherein said housings have rounded tops.
 9. A switch as claimed in claim 1 wherein said housings are circular in cross-section.
 10. A switch as claimed in claim 1 wherein said casing and push button are constituted of transparent plastic material. 